hi there I am making a costume for an upcoming event. For this I am dyeing a chefs coat that is 65/35 poly/cotton blend and my two options are to dye it a fairly light grey or dark black. I tryed a black dye that only works for natural fiber and it did not come out the grey it should be mostly because the non colored threads were to prominent. I am considering mixing idye with idye poly to make it black. but I dont want it to be too light a color for black but to dark to be grey. please help